Oil suction device of vehicle

ABSTRACT

An oil suction device of a vehicle has a mechanical oil pump and includes an air suction unit. The air suction unit includes a first communication passage, a second communication passage, and an opening and closing mechanism. The first communication passage communicates with an atmosphere side. The second communication passage communicates with a suction unit of the oil pump. The opening and closing mechanism is capable of switching between opening and closing of communication between the first communication passage and the second communication passage. When an oil suction pressure of the oil pump becomes a negative pressure lower than or equal to a predetermined pressure, the opening and closing mechanism is opened to cause air sucked through the air suction unit to be mixed into oil which is sucked from an oil reservoir through a suction pipe.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. $119 to JapanesePatent Application No. 2013-116637, filed Jun. 3, 2013, entitled “OilSuction Device of Vehicle.” The contents of this application areincorporated herein by reference in their entirety.

BACKGROUND

1. Field

The present disclosure relates to an oil suction device of a vehicle.

2. Description of the Related Art

Conventional oil pumps used for transfer of lubrication oil for gearsand rotation shafts or the like and for cooling oil (lubricating oil andhydraulic oil) in a transmission mounted on a vehicle include amechanical oil pump (gear pump) which is driven by rotation transmittedfrom a driving source of a vehicle such as an engine. In designing thistype of oil pump, for setting necessary flow rate, a safety factor isincorporated based on the past record and experience values so as toensure a necessary oil flow rate in a rotation region with a rotationrate lower than a predetermined rotation rate. For this reason, in ahigh rotation region with a rotation rate exceeding the predeterminedrotation rate, oil is sucked with a flow rate more than necessary. Thus,in such a mechanical oil pump, wasteful driving torque (pump drivingforce) occurs in a high rotation region with a rotation rate exceedingthe predetermined rotation rate, and thus the driving torque causes aloss to a driving source such as an engine.

For this problem, a mechanism that changes a flow rate or a mechanismthat reduces a pump rotation rate is generally adopted as a mechanismfor reducing the driving torque of a mechanical oil pump. As a mechanismthat changes a flow rate, a mechanism (variable flow pump with a reliefcircuit) using a combination of a hydraulic pressure sensitive spoolvalve and a relief circuit has been proposed, for example, as disclosedin Japanese Unexamined Patent Application Publication No. 7-233787. Inaddition, as a mechanism that controls a pump rotation rate, a mechanismto reduce a pump rotation rate using a planetary gear has been proposed,for example, as disclosed in Japanese Unexamined Patent ApplicationPublication No. 2005-207357.

SUMMARY

According to one aspect of the present invention, an oil suction deviceof a vehicle has a mechanical oil pump which is driven by rotationtransmitted from a driving source of the vehicle and configured to suckand pump oil in an oil reservoir to the oil pump. The oil suction deviceincludes an air suction unit. The air suction unit is provided in asuction section in which oil in the oil reservoir is sucked by a suctionunit of the oil pump. The air suction unit includes a firstcommunication passage, a second communication passage, and an openingand closing mechanism. The first communication passage communicates withan atmosphere side. The second communication passage communicates withthe suction unit of the oil pump. The opening and closing mechanism iscapable of switching between opening and closing of communicationbetween the first communication passage and the second communicationpassage. When an oil suction pressure of the oil pump becomes a negativepressure lower than or equal to a predetermined pressure, the openingand closing mechanism is opened to cause air sucked through the airsuction unit to be mixed into oil which is sucked from the oil reservoirthrough a suction pipe.

According to another aspect of the present invention, an oil suctiondevice of a vehicle includes a mechanical oil pump, a first conduit, asecond conduit, and an air suction device. The mechanical oil pump is tobe driven by a driving source of the vehicle and has a suction portion.The first conduit is connected to the suction portion of the mechanicaloil pump. The second conduit is connected to an oil reservoir. The airsuction device includes a first communication passage, a secondcommunication passage, and an opening and closing mechanism. The firstcommunication passage communicates with an atmosphere side. The secondcommunication passage communicates with the first conduit and the secondconduit. The opening and closing mechanism is configured to connect ordisconnect the first communication passage and the second communicationpassage. The opening and closing mechanism connects the firstcommunication passage and the second communication passage in a case inwhich an oil suction pressure in the oil pump becomes a negativepressure lower than or equal to a predetermined pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings.

FIG. 1 is a schematic diagram illustrating an oil suction deviceaccording to an embodiment of the present disclosure.

FIGS. 2A and 2B illustrate an oil pump; FIG. 2A is a view illustratingthe entire configuration of the oil pump; and FIG. 2B is across-sectional view of an air suction valve taken along line IIB-IIB.

FIGS. 3A and 3B are each a cross-sectional view for illustrating theoperation of the air suction valve.

FIG. 4 is a graph illustrating a relationship between oil pump rotationrate and pump suction pressure.

FIG. 5 is a graph illustrating a relationship between oil pump rotationrate and pump torque.

FIG. 6 is a graph illustrating a relationship between oil pump rotationrate and pump flow rate.

DESCRIPTION OF THE EMBODIMENTS

The embodiments will now be described with reference to the accompanyingdrawings, wherein like reference numerals designate corresponding oridentical elements throughout the various drawings.

Hereinafter, an embodiment of the present disclosure will be describedin detail with reference to the accompanying drawings. FIG. 1 is aschematic diagram illustrating an oil suction device according to anembodiment of the present disclosure. FIGS. 2A and 2B illustrate an oilpump; FIG. 2A is a view illustrating the entire configuration of the oilpump; and FIG. 2B is a cross-sectional view of an air suction valvetaken along line IIB-IIB. As illustrated in FIG. 1, an oil suctiondevice 1 includes a mechanical oil pump 10 which is driven by rotationtransmitted from an engine (not illustrated) serving as a driving sourceof a vehicle, a suction pipe 30 which is connected to a suction end 10 aof the oil pump to suck oil in an oil bath (oil reservoir) 2, and adischarge pipe 60 connected to a discharge end 10 b of the oil pump.

The oil pump 10 is used for lubrication of mechanical structure such asgears and for transfer of hydraulic fluid (oil) for cooling in atransmission for a vehicle. The oil pump 10 is a mechanical oil pumpwhich is driven by rotation transmitted from a crankshaft (notillustrated) that rotates by the driving force of the engine. The oilpump 10 includes a pump unit 15 for pumping oil, a suction port (suctionunit) 11 for sucking oil through the suction pipe 30 to the pump unit15, and a discharge port 13 for discharging oil from the pump unit 15 tothe discharge pipe 60. The pump unit 15 is a positive displacementtrochoid pump that includes an outer rotor 16 rotatably supported in acasing 12, and an inner rotor 17 rotatably supported inside the outerrotor 16. In the oil pump 10, the amount of oil pumped by the pump unit15 is increased or decreased according to an increase or decrease in therotation transmitted from the engine.

The oil pump 10 of the present embodiment includes an air suction valve(air suction unit) 20 provided between an atmosphere side 100 and thesuction port 11. The air suction valve 20 includes a first communicationpassage (atmospheric opening) 21 that communicates with the atmosphereside 100, a second communication passage 22 that communicates with thesuction port 11, and a valve mechanism (open/close mechanism) 23 thatallows communication between the first communication passage 21 and thesecond communication passages 22 when the suction pressure of the oilpump 10 becomes a negative pressure lower than or equal to apredetermined pressure (prespecified pressure). The valve mechanism 23has a housing portion 24 formed between the first communication passage21 and the second communication passage 22, a spherical valve element 25housed in the housing portion 24, and a coil spring (urging unit) 26that urges the valve element 25. The valve element 25 is movable betweena closed position and an open position in the housing unit 24, theclosed position at which the valve element 25 is seated on a valve seat27 which is formed in the periphery of the first communication passage21, the open position being spaced away from the valve seat 27. The coilspring 26 urges the valve element 25 toward the closed position at whichthe valve element 25 is seated on the valve seat 27. When the oilsuction pressure of the oil pump 10 becomes a negative pressure lowerthan or equal to a predetermined pressure, the valve element 25 movesagainst the urging force of the coil spring 26 from the closed positionto the open position.

FIGS. 3A and 3B are each a cross-sectional view for illustrating theoperation of the air suction valve 20. In a state where the oil suctionpressure of the oil pump 10 is higher than a predetermined pressure, theresultant force of the urging force of the coil spring 26 applied to thevalve element 25 and the force applied from the hydraulic oil of thesuction port 11 is greater than the force applied from the atmosphereside 100 through the first communication passage 21. Therefore, thevalve element 25 seals between the first communication passage 21 andthe second communication passages 22 with the valve element 25 seated onthe valve seat 27 due to the urging force of the coil spring 26. Whenthe oil suction pressure of the oil pump 10 is in a negative pressurestate lower than or equal to the predetermined pressure, the forceapplied from the atmosphere side 100 through the first communicationpassage 21 is greater than the resultant force of the urging force ofthe coil spring 26 applied to the valve element 25 and the force appliedfrom the hydraulic oil of the suction port 11. Consequently, the valveelement 25 moves away from the valve seat 27 against the urging force ofthe coil spring 26, thereby allowing communication between the firstcommunication passage 21 and the second communication passages 22. Inthis manner, a first suction operational state and a second suctionoperational state are switched therebetween according to a suctionpressure of the oil in an oil bath 2 caused by the oil pump 10, thefirst suction operational state allowing only the oil in the oil bath 2to be sucked through the suction pipe 30, the second suction operationalstate allowing the oil in the oil bath 2 to be sucked through thesuction pipe 30 and allowing air to be sucked through the air suctionvalve 20.

In the first suction operational state, only oil is sucked through thesuction pipe 30 by the operation of the oil pump 10 and air is notsucked through the air suction valve 20. In the first suctionoperational state, air is not sucked into the oil pump 10, and thereby alinear increase in oil flow rate is obtained, the linear increase beingapproximately proportional to the rotation rate of the oil pump 10. Inthe second suction operational state, oil is sucked through the suctionpipe 30 and air is sucked through the air suction valve 20 by theoperation of the oil pump 10. Because the air sucked through the airsuction valve 20 is mixed into the oil pump 10, an increase in pumpnegative pressure and pump driving force is maintained to be low (incontrast to a state in which no air is mixed). That is, the oil suctiondevice 1 in the present embodiment is capable of limiting the amount ofoil suction and reducing the hydraulic pressure power of the oil pump 10by mixing air into the oil which is sucked into the oil pump 10. In thismanner, by mixing the air sucked through the air suction valve 20 intothe oil which is sucked through the oil bath 2, the amount of oilsuction in relation to the rotation rate of the oil pump 10,particularly, in a high rotation region may be reduced to a lower level.

FIGS. 4 to 6 are graphs for illustrating performance comparison betweenthe oil suction device 1 in the present embodiment and an oil suctiondevice in a conventional configuration. FIG. 4 is a graph illustrating arelationship between the rotation rate (input rotation rate) and pumpsuction pressure of the oil pump 10; FIG. 5 is a graph illustrating arelationship between the rotation rate and pump torque of the oil pump10; and FIG. 6 is a graph illustrating a relationship between therotation rate and pump flow rate of the oil pump 10. In FIGS. 5 and 6,the graph for the oil suction device 1 in a conventional configurationis indicated by a solid line, and the graph for the oil suction devicein the present embodiment is indicated by a dotted line. The oil suctiondevice in a conventional configuration herein does not include the airsuction valve 20 according to the present embodiment.

In the oil pump 10 in the present embodiment, as illustrated in FIG. 4,in the region where pump rotation rate N is lower than a predeterminedrotation rate N1, pump suction pressure P is higher than a predeterminedpressure (prespecified negative pressure) P1 (P>P1), and in the regionwhere the pump rotation rate N is higher than or equal to thepredetermined rotation rate N1, the pump suction pressure P is lowerthan or equal to the predetermined pressure (prespecified negativepressure) P1 (P≦P1). Thus, in the region where the pump rotation rate Nis lower than the predetermined rotation rate N1, the oil pump 10 is inthe first suction operational state in which only oil is sucked throughthe suction pipe 30, and in the region where the pump rotation rate N ishigher than or equal to the predetermined rotation rate N1, the oil pump10 is in the second suction operational state (air mixed state) in whichair sucked through the air suction valve 20 is mixed into the oil whichis sucked through the suction pipe 30. Thereby, as illustrated in thegraph of FIG. 6, in contrast to the oil suction device in a conventionalconfiguration, an increase in the flow rate of the sucked oil may bereduced (rate of increase may be reduced) in a high rotation region withthe predetermined rotation rate N1 or higher. Therefore, as illustratedin FIG. 5, a pump torque reduction effect is achieved. Consequently,pumping loss and transmission loss may be reduced.

As described above, in the oil suction device 1 in the presentembodiment, equipped with the mechanical oil pump 10 which is driven byrotation transmitted from a driving source of a vehicle, the suctionport 11 of the oil pump 10 is provided with the air suction valve 20.The air suction valve 20 includes the first communication passage 21which communicates with the atmosphere side 100, the secondcommunication passage 22 which communicates with the suction port 11,and the valve mechanism (open/close mechanism) 23 which is capable ofswitching between opening and closing of communication between the firstcommunication passage 21 and the second communication passage 22. Theair suction valve 20 is configured to open the valve mechanism 23 whenthe oil suction pressure of the oil pump 10 becomes a negative pressurelower than or equal to the predetermined pressure, and air suckedthrough the air suction valve 20 is thereby mixed into the oil which issucked from the oil bath 2 through the suction pipe 30.

The oil suction device 1 in the present embodiment has a configurationin which the above-described air suction valve 20 is provided in asuction section in which oil in the oil bath 2 is sucked by the oil pump10, and when the oil suction pressure of the oil pump 10 becomes anegative pressure lower than or equal to the predetermined pressure, airis sucked by the oil pump 10 through the air suction valve 20 to reducethe driving torque of the oil pump 10. Thus, it is possible to reduce apump driving torque particularly for an excessive amount of discharge ina high rotation region with a rotation rate exceeding the predeterminedrotation rate. Therefore, the driving torque of a driving source whichtransmits rotation to the oil pump 10 may be reduced, and loss to thedriving source may be effectively reduced.

In this manner, a configuration is adopted in which the air suctionvalve 20 is provided in a suction section in which oil in the oil bath 2is sucked by the oil pump 10, the air suction valve 20 serving as amechanism which changes the distribution (selectively sucks air and oil)between the amount of suction of oil in the oil bath 2 and the amount ofsuction of air, and thus the driving torque of the oil pump 10 isintentionally reduced by causing the oil pump 10 to suck air. That is,by providing a unit for sucking air on a suction path of the oil pump10, an excessive amount of oil sucked by the oil pump 10 may beregulated when the suction pressure of the oil pump 10 is a negativepressure lower than or equal to the predetermined pressure, and thus atorque necessary for driving the oil pump 10 may be reduced. This makesit possible to reduce a pump driving torque particularly for anexcessive amount of discharge in a high rotation region with a rotationrate exceeding the predetermined rotation rate. Consequently, thedriving torque of the engine (driving source) that drives the oil pump10 may be effectively reduced.

In the above-described oil suction device, the air suction valve 20includes the valve element 25 that opens and closes between the firstcommunication passage 21 and the second communication passages 22, andthe coil spring (urging unit) 26 that urges the valve element 25 to aclosed position. When the oil suction pressure of the oil pump 10becomes a negative pressure lower than or equal to a predeterminedpressure, the valve element 25 moves against the urging force of thecoil spring 26 from the closed position to the open position by a forceapplied to the valve element 25.

With this configuration, when the suction pressure of the oil pump 10becomes higher than or equal to the predetermined pressure, air may besucked into the oil pump 10 using a simple configuration with a lessnumber of components.

So far, the embodiment of the present disclosure has been described,however, the present disclosure is not limited to the above-describedembodiment and various modifications may be made in a scope of thetechnical concepts described in the claims, the description and thedrawings. For example, the specific structure of the air suction valve20 in the above-described embodiment is an example. The air suction unitincluded in the oil suction device according to an embodiment of thepresent disclosure is not limited to have the structure as in the airsuction valve 20 and may have another structure as long as the airsuction unit has a structure capable of switching between open andclosed positions according to a suction pressure of the oil pump. In theabove-described embodiment, the case has been illustrated in which theair suction valve is provided in the suction port of the oil pump.However, the air suction unit according to an embodiment of the presentdisclosure may be provided at a position other than the positionspecified in the embodiment as long as the air suction unit is providedin the suction section in which oil in the oil reservoir is sucked bythe oil pump (pump unit).

Provided is an oil suction device of a vehicle according to anembodiment of the present disclosure, the oil suction device (1) havinga mechanical oil pump (10) which is driven by rotation transmitted froma driving source of the vehicle and configured to suck and pump oil inan oil reservoir (2) to the oil pump (10), the oil suction deviceincluding an air suction unit (20) which is provided in a suctionsection in which oil in the oil reservoir (2) is sucked by a suctionunit (11) of the oil pump (10), the air suction unit (20) including afirst communication passage (21) which communicates with an atmosphereside (100), a second communication passage (22) which communicates withthe suction unit (11) of the oil pump (10), and an opening and closingmechanism (23) which is capable of switching between opening and closingof communication between the first communication passage (21) and thesecond communication passage (22). When an oil suction pressure (P) ofthe oil pump (10) becomes a negative pressure lower than or equal to apredetermined pressure (P1), the opening and closing mechanism (23) isopened to cause air sucked through the air suction unit (20) to be mixedinto oil which is sucked from the oil reservoir (2) through a suctionpipe (30).

The oil suction device of a vehicle according to an embodiment of thepresent disclosure has a configuration in which the above-described airsuction unit is provided in a suction section in which oil in the oilreservoir is sucked by the suction unit of the oil pump, and therebywhen the oil suction pressure of the oil pump becomes a negativepressure lower than or equal to the predetermined pressure, air issucked by the oil pump through the air suction unit to reduce thedriving torque of the oil pump. With this configuration, it is possibleto reduce a pump driving torque particularly for an excessive amount ofdischarge in a high rotation region with a rotation rate exceeding apredetermined rotation rate. Therefore, the driving torque of a drivingsource which transmits rotation to the oil pump may be reduced, and lossto the driving source may be effectively reduced.

The above-described air suction unit has a structure which allowsswitching between enabling and disabling of suction of air into the oilpump according to an oil suction pressure. Thus, when the rotation rateof the oil pump is in a high rotation region and the suction negativepressure increases, air may be mixed into the oil which is to be suckedin the oil pump. Therefore, it is possible to reduce an increase in theamount of sucked oil in a high rotation region of the oil pump, and aneffect of reduction in pump drive force and an effect of decrease insuction negative pressure are achieved. Consequently, the driving torqueof the driving source may be reduced with a simple configuration.

In the above-described oil suction device, the opening and closingmechanism (23) includes: a valve element (25) configured to open andclose between the first communication passage (21) and the secondcommunication passages (22); and an urging unit (26) configured to urgethe valve element (25) to a closed position. When the oil suctionpressure (P) of the oil pump (10) becomes a negative pressure lower thanor equal to the predetermined pressure (P1), the valve element (25)moves against an urging force of the urging unit (26) from the closedposition to an open position.

With this configuration, when the suction pressure of the oil pumpbecomes higher than or equal to the predetermined pressure, air may besucked into the oil pump using a simple configuration with a less numberof components. The symbols in the above parentheses are provided so thatthe symbols of the components in the below-described embodiment are eachillustrated as an example in the present disclosure.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. An oil suction device of a vehicle, the oil suction device having a mechanical oil pump which is driven by rotation transmitted from a driving source of the vehicle and configured to suck and pump oil in an oil reservoir to the oil pump, the oil suction device comprising an air suction unit which is provided in a suction section in which oil in the oil reservoir is sucked by a suction unit of the oil pump, the air suction unit including a first communication passage which communicates with an atmosphere side, a second communication passage which communicates with the suction unit of the oil pump, and an opening and closing mechanism which is capable of switching between opening and closing of communication between the first communication passage and the second communication passage, wherein when an oil suction pressure of the oil pump becomes a negative pressure lower than or equal to a predetermined pressure, the opening and closing mechanism is opened to cause air sucked through the air suction unit to be mixed into oil which is sucked from the oil reservoir through a suction pipe.
 2. The oil suction device of a vehicle according to claim 1, wherein the opening and closing mechanism includes: a valve element configured to open and close between the first communication passage and the second communication passages; and an urging unit configured to urge the valve element to a closed position, wherein when the oil suction pressure of the oil pump becomes a negative pressure lower than or equal to the predetermined pressure, the valve element moves against an urging force of the urging unit from the closed position to an open position.
 3. An oil suction device of a vehicle, comprising: a mechanical oil pump to be driven by a driving source of the vehicle and having a suction portion; a first conduit connected to the suction portion of the mechanical oil pump; a second conduit connected to an oil reservoir; and an air suction device comprising: a first communication passage which communicates with an atmosphere side; a second communication passage which communicates with the first conduit and the second conduit; and an opening and closing mechanism configured to connect or disconnect the first communication passage and the second communication passage, the opening and closing mechanism connecting the first communication passage and the second communication passage in a case in which an oil suction pressure in the oil pump becomes a negative pressure lower than or equal to a predetermined pressure.
 4. The oil suction device of a vehicle according to claim 3, wherein the opening and closing mechanism includes a valve element configured to connect or disconnect the first communication passage and the second communication passages, and an urging device configured to urge the valve element to a closed position at which the first communication passage and the second communication passages are disconnected, and wherein when the oil suction pressure of the mechanical oil pump becomes a negative pressure lower than or equal to the predetermined pressure, the valve element moves against an urging force of the urging device from the closed position to an open position at which the first communication passage and the second communication passages are connected.
 5. The oil suction device of a vehicle according to claim 3, wherein when a pump rotation rate of the mechanical oil pump is higher than or equal to a predetermined rotation rate, the oil suction pressure of the mechanical oil pump becomes a negative pressure lower than or equal to the predetermined pressure. 